Sheet material



April17, 1945'. N 'ATWOOD 2,373,738

` A SHEET MATERIAL Filed Nov. 1, 1941 Fg l. /l/O @AWWA lng the laminated sheet y invention.

PneniedApr. 17, 194s UNITEDv Y's-'ni'rlas PATENT OFFICE 1 2,373,738 l SHEET MATERIAL Harry N. Atwood, Meueawis. Application November 1, 1941, Serial No. 417,457

2 Claims.

This invention relates to sheet material and more ,particularly to laminated sheet material formed of interwoven or interlocked strips or ribbons and bonded together bymeans of a plastic.

In my Patent No. 2,126,711, dated August 16, 1938, I have disclosed and claimed sheet material of the general type of construction as that which is formed into a laminated sheet material in accordance with the present invention. In'- stead of merely laminating two sheets of light interwoven material, however, I form the sheets to be laminated of different widths of ribbon or stripomaterial, or with the ribbon or strip material in the adjacent laminations `at different angles to each other, so that the lateral edges of the ribbon or strip material are for the most part non-coincidental. I have found that by so do- Cil ing the strength'of the laminated material is greatly increased,as is also its resistance toward cracking.

It is therefore an important object of thisy invention to provide sheet material composed of laminations of interwoven or interlocked strip material, wherein the strips in adjacent laminations are either of dissimilar width or arranged at different angles with respect to one another so that the lateral edges of the strips in adjacent laminations will be non-coincidental, or out of registration with one another.

Other and further' important objects of this invention willbe apparent from the disclosures in the specification and the accompanying drawmg.. 5 l

This invention (in a preferred form) ls illustrated in the drawing and hereinafter more fully described.

0n the drawing:

Figure l is a plan view of woven sheet material of a singlethickness such as may be used in makmateal of the present Figure 2 is a plan view of similar woven sheet material but with the ribbons or strips thereof relatively narrower than the ribbonsor strips of the sheet material of Fig. 1.

Figure 3 is aplan view of the finished, laminated sheet material of my invention, with the upper laminations broken away to show the lower laminations.

Figure 4 is an enlarged fragmentary sectional view of the sheet material of Figs. 1 and 2 before being laminated together.-

Figure 5 is an enlarged fragmentary sectional view of the. ilnished laminated sheet material 0f Fig. 3.

strips II are coated with a plastic material before being interwoven into the sheet I0 and, after being woven intothe form of sheets, which may be more or lesscontinuous in character, the woven material is subjected to a pressing operation to cause` an interlocking of the ribbons orstrips II without, however, breaking or rupturing the fibers loi' the veneer or other fibrous material constituting the strips or ribbons. During this pressing operation, the plastic material flows around and between the strips or ribbons I I to wholly encase said strips or ribbons. while ,atv the same time separating the individual strips or ribbons from each other, the plastic material being indicated by the reference `numeral-I2l (Figs. 4 and 5). l

A second. sheet of material, indicated by the reference numeral I3 (Fig. 2) is made up in a similar way to the sheet III except that the strips or ribbons I4 of said sheet I3 are) relatively narrower than the strips or ribbons II 'of the sheet III. The individual stripsor ribbons Ilare likewise encased within and coated with a plastic I5,

which is preferably the same type of plastic as the plastic I2 of the sheet III. The sheets III and' 'formed by the original sheet I0 do not coincide or register with the lateral -edges Il of the strips or ribbons- I4 of the laminations formed by the loriginal sheet I3. Because of the difference in. the width of the strips or ribbons I I and I 4, their respective .lateral edges I1\and I8 -can be offset from one another in superimposing the sheets I0 and I3 to form the laminations ofthe final laminated sheet material II.- This arrangement materially increases the strength of the finished 4 laminated sheet material over thatfwliich might be obtained ifthe strips or ribbons of the adia- I3. Thus, when mosetting plastic material may 2 cent laminations were of the same width and their lateral edges were coincidental.

A somewhat similar result is obtained by arranging the strips of adjacent laminations at different angles. As illustrated in Fig. 6, a sheet I9 may be made up of interwoven strips 20 arranged 1n a different angular relationship than that of either the strips or ribbons Il of the sheet I or thestrips or ribbons Il of the sheet a sheet such as I9 is laminated to a sheet such as Il or I3, the lateral edges oi the strips or ribbons in adjacent laminations are for the most part non-coincidental. Where the strips or ribbons forming the sheet material are cut from lwond veneer, the grain of the wood is generally longitudinally of the strips, so that lwith the strips arranged at different angles in adjacent laminations, the grains in the wood veneers of the adjacent laminations would also be at an angle, thereby increasing the strength of the nished laminated sheet material.`

While the material l2 and I5 has been referred to generally as plastic material, it will be understood that either a thermoplastic or a therbe used. While I have found that thermoplastic materials are preferable, especially in the manufacture of aircraft skins because of the greater ease of construction and repair, thermosetting resins may nevertheless be entirely suited where the laminated sheet material is to be used for other pur poses. Among the thermoplastic materials that have been found satisfactory may be mentioned the cellulosic derivatives, such as cellulose acetate,

cellulose ethers and the like, poly vinyls, poly styrenes and many others. Thermosetting resins, such as phenol-formaldehyde type of resins, the urea-formaldehyde type of resins, and' numerous 'others are available for'use where the characteristics of such thermosetting resins are such as .to adapt the finished laminated material to the uses and purposesffor which it is intended.

It will, of course, be understood that various -details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims. Y

I claim as my invention:

1. Self-sustaining sheet material comprising a. plurality of laminations of interlocked, form retaining strips encased in 'a plastic, the strips in adjacent laminations being of different width with lateral edges thereof disposed in generally1 non-.coincidental relationship.

2; Self-sustaining sheet material comprising a plurality of laminations of interlocked wood 'veneer strips encased in a thermoplastic, the strips in adjacent laminations being of different width with .lateral edges thereof disposed in generally non-coincidental relationship.

' HARRY N. ATWOOD. 

